(1) Field of the Invention
The present invention relates generally to three-dimensional braiding technology, more particularly, to three-dimensional braiding machines and methods of manufacturing braided preform structures therewith.
(2) Description of the Prior Art
Braided textile structures have been manufactured by hand for many years. Also, it is known in the prior art to use machines for braiding and for the manufacture of braided preforms, perhaps even as early as 1770 when Mr. Bockmuhl built a braiding machine in Barmen. The 3-dimensional braiding process is a further improvement and substantial development over the 2-dimensional braiding of structures like xe2x80x9cLitzenxe2x80x9d and cordage. In 3-D braiding processes, the braiding yarn runs throughout the braided structure in all three dimensions. Thus, the structures of 3-D braids offer special properties, e.g., high torsion strength. Moreover, typically, it is known to use braided performs for composites and laminated structures for a variety of applications. Additionally, the use of high performance fibers for making multilayer preforms is known in the art.
The present invention is applicable to the design and manufacturing of a broad variety of cross-sectional shapes and dimensions of three-dimensional (3-D) braided fiber preforms and structures for a multiplicity of applications, including but not limited to preforms for making composite structures for aerospace and commercial aircraft, infrastructure, industrial and commercial components, and other applications. The design of machines for braiding has developed with the growing success and interest in high performance composite structures, in particular three-dimensional woven and braided preforms for use in composites, due to their high specific stiffness and strength, fatigue life, corrosion resistance, thermostability, and dimensional stability in a wide range of temperatures and agressive environments,
Prior art machines have been limited in, most importantly, control, speed, dimension, and precision. More particularly, prior art machines have been unable to provide a density of yarn carriers that would permit the machine to make sufficiently large cross-sections for practical applications, much less a variety of cross-sectional shapes and their continuous variation along the braided part. By way of example, the 3-D rotational braiding machine manufactured by the company August Herzog employs a system that works with Geneva wheels, which is very similar to conventional braiding systems. This prior art braiding machine is based on the net-braiding machine, which allows the production of a net-braided structure through a systematically braided connection of small braids. Each Geneva wheel must be connected with the drive assembly and the brake mechanism which is necessary for the rotation and exact position of the Geneva wheel and the handing over process of the bobbins. Disadvantageously, the construction of the Geneva wheels requires a relatively high fell, or braiding point.
Also, disadvantageously, the machine dimensions affect the yarn compensation length. To balance the yarn compensation length, it is necessary to use an up-and-down wind balance system that can be controlled by a torsion arm. Hence, there are special problems using carbon and glass yarns, which are very sensitive to any torsion and redirections. Thus, there remains a need for a method and machine for that is sized and configured to work without space and control limitations and restrictions for yarn types that can work on machines of the prior art.
Additionally, it is known in the art to use a bobbin tip principle for 3-D braiding processes and machines. This type of system works without intersections, with smaller working place requirements and a special method of construction to minimize the yarn compensation length; also it is based on an interlacing or knocking process with only one yarn control system, with modified Geneva wheels that have two notches for working space in the third dimension, i.e., a bobbin can be configured in the working area of two Geneva wheels and can be controlled by them. However, the Geneva wheels have a defined curve that does not work with any intersection; this configuration only permits hemispherical arrangements and provides limited freedom of movement of the bobbins throughout the braided structure. Thus there remains a need for a method and machine that permits 3-D braiding of complex structures in a compact machine configuration.
Furthermore, machines of prior art could not produce wall-thickness sufficient to withstand further processing, much less provide adequate finished composite properties. Importantly, machines and methods of making braided fiber preforms according to the prior art have been unable to provide uninterrupted transition between components having different cross-sectional shapes and dimensions without making substantial changes to the machine configuration and/or yarn or fiber supply.
Thus, there remains a need for a machine and method for producing complex-shaped, three-dimensional engineered fiber preforms that may be used as mechanical components, more particularly, a complex shaped three-dimensional braided fiber preform formed and constructed of a unitary, integral construction including a plurality of fibers that are capable of producing a variety of cross-sectional shapes and sizes in a continuous series on a single machine.
The present invention is directed to a machine and method for producing complex shaped, three-dimensional engineered fiber preforms having unitary, integral and seamless structure and rigid composite structure made therefrom for use as a mechanical component, particularly for use as a T- and J-stiffener structures, I-beam structures, box-beam structures, tubular and circular cross-section beam structures, engine valves, and similar structures, and method for making the preform.
Preferably, a particular embodiment of the invention is a machine for forming 3-D braided structures having an integral design formed by selective combination of sets of straight yarns or fiber systems and interlacing continuous reinforcing yarns or fiber systems. The machine or device of a preferred embodiment according to the present invention includes the combined mechanical scheme for 3-D braiding, produces various types of axis-symmetric and non-symmetric braiding architectures, most particularly those having complex cross-sectional shapes, including, but not limited to rectangular-shaped structures, as well as cylindrical, conical, and radial yarn placement that can be used to make a variety of 3-D braided preforms, including but not limited to specific components like an integral engine valve with continuously variable reinforcement architecture at various zones of the valve.
Additionally, any of the various cross-sectional shapes may be manufactured on a single machine according to the present invention. The machine having at least one modular group (FIG. 3c) that includes two identical cells (FIG. 3a) and a gripping fork (2 in FIG. 3b) with its individual drive (6 in FIG. 3b) connecting the cells. Each cell consists of a horngear (1 in FIGS. 2a, 3a), drive shaft (8), gear (7), four carrier drivers (3 in FIGS. 2b, 3a), and at least two yam carriers or spindles (the case of four spindles is illustrated in FIG. 3a). Advantageously, the compact design of a horngear (FIG. 2a), carrier driver (FIG. 2b) and gripping fork (FIG. 2c) configurations enable to assemble any number of cells in machine module via innovative gate design (FIGS. 2d and 3c) for providing smooth transition of each of the at least two spindles from one cell to another. In addition to a minimum of two movable yarn carriers that are part of a cell, axial yarns can also be supplied through central holes in the horngear (shown in FIGS. 2a, 2d) from stationary bobbins placed outside the machine. A single machine module includes at least one modular group (FIGS. 2d, 3c) but is not limited to any particular number of modular groups.
The present invention is further directed to a method for making a complex shaped, three-dimensional engineered fiber preforms having a unitary, integral and seamless structure.
Accordingly, one aspect of the present invention is to provide a machine for automatically producing complex-shaped, three-dimensional engineered fiber preforms having unitary, integral and seamless structures for use in making rigid composite structure made therefrom for providing increased component stiffness, strength, durability, and stability.
Another aspect of the present invention is to provide a method for making complex-shaped, three-dimensional engineered fiber preforms having a unitary, integral and seamless structures on a single one-module machine that is scalable via adding modular groups to produce large dimensions and varied cross-sectional shapes.
Still another aspect of the present invention is complex-shaped, three-dimensional engineered fiber preforms having unitary, integral and seamless structures made on a single multi-modular machine that is scalable via adding modules or modular groups of cells to produce large dimensions and varied cross-sectional shapes.
Yet another aspect of the present invention is to provide a machine for making complex-shaped, three-dimensional engineered fiber preforms having unitary, integral and seamless structures made on a single multi-modular machine having a control system that permits selective activation and deactivation of modular groups such that changing the combination of activated modular groups changes the cross-sectional shape of the preform produced on the machine.
These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.